Reversible counting devices



March 26; 1968 N.YUDE WITZ: 3,375,349

REVERSIBLE COUNTING DEVICES Filed Sept. 3, 1964 2 Sheets-Sheet 1 INVENTOR n Yudewitz Fl 6.3

ORNEY March 26, 1968 D T I 3,375,349

REVERSIBLE COUNTING DEVICES Filed Sept. 5, 1964 2 Sheets-Sheet 2 mm. \\\\\\1 n\\\\\\\\ U no I08 E Y 423 l\\\\ \V F! \\\\\\\3 m as INVENTOR Norman Y udewifiz u w/w ATTORNEY United States Patent Ofiiice 3,375,349 Patented Mar. 26, 1968 3,375,349 REVERSIBLE COUNTING DEVICES Norman Yudewitz, Westport, Conn., assignor to American Machine & Foundry Company, a corporation of New Jersey 1 Filed Sept. 3, 1964, Ser. No. 394,277 6 Claims. (Cl. 235-92) ABSTRACT OF THE DISCLOSURE This invention relates to a simple and effective drive means for accomplishing bi-directional relative movement between a magnetizable disc and a read head to accomplish add-subtract functions.

This invention relates to reversible counting devices, and more specifically to electromechanical reversible counting and memory devices.

In the design of digital systems in which it is necessary to command the occurrence of an event, or a series of events, contingent on the presence of a particular number of items, or following the occurrence of another event a predetermined number of times, a need arises for a relatively simple and reliable counter or totalizer. The prior art includes a wide variety of electronic devices and some mechanical devices which can perform at least part of this function.

Generally, the electronics systems are quite complex and, because of the active elements involved, are expensive to construct and maintain. Those devices which can be broadly categorized as mechanical are similarly complex, and often difficult to maintain for reliable and accurate operation. A primary drawback of prior systems, both electronic and mechanical, is that they are usually capable of performing only a particular function in a particular system, and do not have sufiicient flexibility to allow their use in any other system without extensive modification.

A general object of the present invention is to provide a reversible counting device which is simple and reliable.

A further object is to provide an electromechanical reversible counting device which can be reprogrammed to control external apparatus without mechanical modification.

The present invention employs, as a basic component, a magnetizable disc, the surface of which can be selectively magnetized in any desired pattern. One or more reed switches are disposed to respond to the presence of magnetized zones of the disc and to control the operation of an external device in response to the information program of the magnetic pattern, or to control the operation of the counter itself. Unidirectional stepping motors are used to rotate the disc and the switch relative to each other in distinct angular steps in response to add or subtract pulses supplied to the stepping motors.

In order that the manner in which the foregoing and other objects are attained in accordance with the invention can be understood in detail, particularly advantageous embodiments thereof will be described with reference to the accompanying drawings, which form a part of this specification, and wherein:

FIG. 1 is a side elevational view of a reversible counter in accordance with one embodiment of the invention;

FIG. 2 is a plan view of a portion of the device of FIG. 1;

FIG. 3 is a plan view of one type of unidirectional motor which may be used in accordance with the invention;

FIG. 4 is a side elevational view of a device in accordance with another embodiment of the invention;

FIG. 5 is a side elevational view of a device constructed in accordance with a third embodiment of the invention;

FIG. 6 is a longitudinal sectional view of a sensing transformer used in the device of FIG. 5

Referring now to the drawings, and first to FIG. 1 thereof, it will be seen that a unidirectional motor indicated generally at 1 is provided with an output shaft 2, to which is fixedly attached a beveled gear 3. Motor 1 is of a type which responds to successive individual input pulses, supplied to input terminals thereof, to rotate output shaft 2 through a predetermined angle for each pulse, such a motor being described in greater detail below. A second unidirectional motor indicated generally at 4 has an output shaft 5 to which is fixedly secured another beveletl gear 6. Motor 4 is substantially the same as motor 1 in that the output shaft 5 is caused to rotate in a predetermined direction and through a predetermined angle in response to each pulse applied to the motor 4.

Beveled gears 3 and 6 are in meshing relationship with a third beveled gear 7 and a fourth beveled gear 8, the gears 3, 6, 7 and 8 forming a mechanical differential. Gear 7 is fixedly attached to a shaft 9 journaled for rotation about its longitudinal axis in an interior circular opening in a magnetic recording disc indicated generally at 10. Similarly, gear 8 is fixedly attached to a shaft 11 which is journaled for rotation about its longitudinal axis in the circular opening in disc 10, but displaced from the journal mounting of shaft 9.

Magnetic disc 10 includes a backing plate 12 of a relatively rigid ferrous material such as steel, for example, and a surface layer 13 of a selectively magnetizable material, such as rubber impregnated with barium ferrite, lead ferrite, or strontium ferrite. These materials are capable of being magnetized in discrete spots or lines by a conventional writing head, not shown, the size and resolution of the magnetized spots or lines being primarily functions of the shape of the writing head itself. The magnetic characteristics of the ferrite-impregnated rubber are greatly enhanced when this material is laminated on a sheet of highly permeable material such as steel, as shown in FIG. 1.

A conventional reed switch 14 is secured to a mounting board 15 by strap 16, the mounting board 15 and strap 16 being of a nonmagnetic material, as for example a plastic. The mounting board 1 5 is provided with suitable apertures 17 and 18 accommodating conductors 19 and 20 which connect the reed switch to a device (not shown) to be controlled by the switch 14. As will be apparent to one skilled in the art, the switch 14 is of a type which may be operated by the presence of a magnetic field adjacent thereto. The switch element-s themselves include conductors of small cross sectional area, and of a magnetically permeable material, presence of a magnetic field adjacent one of the conductors causing the ends of the conductors to be attracted to each other, thereby closing the switch. For proper operation, the switch 14 is mounted in close proximity to the surface of the disc 10, the spacing between the switch and the disc being on the order of .020 inch.

Referring now to FIG. 2, it will be seen that the layer 13 of the disc 10 can be magnetized in any of a number of desired patterns, as for example a series of individual spots, as indicated by the shaded areas 25, 26 and 27, or in a continuous strip, as indicated at 28. Also, more than one track of spots or strips may be magnetized on the surface at more than one radial distance from the center of the disc, the pattern being determined by the radial position of the writing head when recording, the rotational speed of the disc at recording, the type of signal applied to the recording head, and the size and shape of the end of the recording head adjacent the disc. As will be recognized, the recording head may be of any known type, as for example a cylindrical core surrounded by a coil to which the signal can be supplied.

Referring now to FIG. 3, it will be seen that one form of the unidirectional motor used in the embodiment of FIGS. 1 and 2 is indicated generally at 1, and comprises an electromagnet indicated generally at 30, including a coil 31 and an armature 32, the armature being adapted to come in contact with a pole 33 when the coil 31 is supplied with energizing voltage. A conductor 34 is connected to one end of the coil 31 and to a power supply input terminal 35. A conductor 36 is connected to the other end of coil 31 and to a second power supply input terminal 38.

The armature 32, which is pivotably attached to the magnetic structure 39 of electromagnet is normally restrained by coil spring 40 so as not to be normally in contact with the pole face 33. When coil 31 is energized, the armature 32 is magnetically attracted to the pole 33'. The end of the extended portion of armature 32 is pivotably attached to a lever arm 42 which is pivotably mounted in a double fulcrum provided by a pin 43 and a pin 44. The other end of lever arm 42 is therefore free to move through an arc limited only by the motion of armature 32. A pawl arm 45 extends through a central opening in lever arm 42 and is held therein by a knife edge 46 formed by cutting and bending a portion of the center of lever arm 42, the knife edge 46 being fitted in a notch 53 provided near one end of pawl arm 45.

A ratchet wheel 47, having a plurality of teeth 48 equally spaced about the periphery thereof, is secured to shaft 2 by a pin 49 which passes through a shoulder 50 of ratchet wheel 47 and into shaft 2. As previously described, shaft 2 is journaled for rotary motion in the base plate 29 of unidirectional motor 1. The other end of pawl 45 is provided with a suitably hook-shaped pawl member 51 adapted to engage the teeth 48 of ratchet wheel 47 and to induce a rotary motion of the ratchet wheel as the pawl 45 is moved. A spring arm 52, for-med in a manner similar to the knife edge 46, by cutting and bending a portion of the center of lever arm 42, is provided to apply pressure to the back of pawl arm 45, thereby maintaining contact between the hook portion 51 of arm 45 and the ratchet teeth 48. A spring stop 54 is secured to a pin 55 and bent so as to intercede between the teeth 48 of ratchet wheel 47, thereby preventing any rotary motion other than the desired unidirectional motion, clockwise as seen in FIG. 3.

In operation, a pulse of relatively short duration is supplied to the supply terminals 35 and 38 and, via conductors 34 and 36, is supplied to the coil 31 of electromagnet 30. This energizing pulse will act to move the armature 32 to the position shown in FIG. 3 against the biasing force of spring 40. Lever arm 42 will then be caused to pivot about the double fulcrum of pins 43 and 44, the free end of arm 42 tending to move away from ratchet wheel 47. This action causes pawl arm 45 to move from the position shown in dotted lines in FIG. 3 to that shown in solid lines, thereby pulling the engaged one of teeth 48 in the same direction and causing ratchet wheel 47 to rotate in a clockwise direction. Spring 54 is bent radially outward during this motion, and, by reason of its own resilience, enters the gap between the next two teeth. Armature 32 and lever arm 42 are dimensioned so that the motion of pawl arm 45 between the energized and de-energized positions is substantially equal to the distance between two teeth, thereby assuring that the rotary motion of ratchet wheel 47 will not exceed the angular distance from one tooth to the next. Thus, immediately after cessation of the pulse, the system is returned to its de-energized state by spring 40, in which state it will remain until occurrence of the next succeeding pulse. It will therefore be seen that the output shaft 2, moving with ratchet wheel 47, will be rotated through an angle equal to the space between teeth 48 in response to each applied input pulse to input terminals 35 and 38.

The desired incremental angular movement of shaft 2 can therefore be selected by the proper choice of tooth spacing.

Returning now to FIGS. 1 and 2, it will be seen that, as each pulse is applied to motor 1, shaft 2 will be rotated in the direction indicated by the arrow about that shaft. Similarly, as motor 4 is supplied with each of a series of pulses, output shaft 5 will be rotated in a direction indicated by the arrow about that shaft. To understand clearly the operation of the system as a counting or totalizing system, we may consider motor 1 to be the add motor and motor 4 to be the subtract motor. It will then be seen that each add pulse applied during a time when no subtract pulse is being supplied will cause shaft 2 and bevel gear 3 to rotate through a small angle. In accordance with the normal operating characteristics of a mechanical differential, with gear 6 held in a fixed position and gear 3 rotated, gears 7 and 8 rotate, carrying with them the entire structure of disc 10. Thus for each add input pulse, disc 10 is rotated through a small angle in one direction. Similarly, for each subtract pulse provided in the absence of a simultaneously occurring add pulse, disc 10 will be rotated in the opposite direction through a small angle. If an add pulse and a subtract pulse occur simultaneously, gears 3 and 6 will move in opposite directions simultaneously, but disc 10 will not move.

Any selected point on the layer 13 of disc 10 is accordingly moved relative to the reed switch 14 in dependence upon the total number of add and subtract pulses applied to motors 1 and 4. If the face of layer 13 were visualized as having numerical calibrations, and if switch 14 were considered to be a pointer, it is obvious that the total number indicated by the pointer after a plurality of add and subtract pulses had been applied to the respective motors would be equal to the algebraic sum of these pulses, having started at zero. Visual as well as electrical readout is obtained by providing a fixed pointer 37, and printed numerals on the disc 10, as shown in FIG. 2.

We may then proceed to visualize an application for the system as described as a counting unit having a maximum count of 22 and a minimum count of zero. We will not ask in this instance that the system provide us with an instantaneous reading at any position of the total count, but that it merely provide a deactivating signal when the count reaches zero, and a similar deactivating signal when the count reaches 22. In a unit in which the ratchet wheel 47 carries 44 teeth, we would proceed to magnetize a track at a radial distance coinciding with the position of one end of reed switch 14 throughout approximately of the disc. This pattern would appear similar to the track 28 in FIG. 2. The conductors leading from reed switch 14 may then be connected to an external switching device capable of preventing the input of further subtract pulses. The zero position of the disc would be that in which the counterclockwise end of the magnetized path is one angular step away from being under the reed switch. In this condition, the reed switch would be deenergized and the external switching device would operate to prevent subtract pulses from being applied to the subtract input motor 4. The counter would therefore be unable to count below zero. A second reed switch may advantageously be mounted adjacent another portion of the disc to detect the presence of the magnetized track portion at that position of the disc equivalent to a count of 22, and to operate an external switching device to prevent the further application of add pulses to motor 1.

With the use of only one track, and by writing discrete spots thereon, as illustrated at 25, 26 and 27, the occurrence of a given event depending upon a particular algebraic sum of input pulses can be controlled by the use of a single reed switch. The use of a plurality of tracks and a corresponding number of reed switches adds to the flexibility of the system considerably.

Note that if permanent magnets were placed in a similar disc, but having nonmagnetic characteristics, similar results in part could be obtained, but the system would then be limited to the particular arrangement of magnets. In the present system, the magnetic information placed on the disc can be removed, modified, or replaced at will by conventional erasing and magnetic writing means.

Referring now to FIG. 4, it will be seen that the mechanical dilferential of FIGS. 1 and 2 can be eliminated, the relative motion being obtained by other means. A unidirectional motor 60, equivalent to the motor 1 of FIGS. 1 and 3, is provided with an output shaft 61 to which is fixedly secured a pair of slip rings 62 and 63. The end of output shaft 61 opposite the motor is externally threaded to receive an arm 64 which can be keyed to shaft 61 and held in place by two internally threaded nuts 65 and 66. The free end of arm 64 carries a reed switch 67 which is secured to the arm by a clamp 68. Suitable apertures are provided in arms 64 to allow conductors 69 and 70 to pass therethrough, the conductors 69 and 70 then being connected to slip rings 63 and 62, respectively. Sliding contact brushes 71 and 72 are held in contact with slip rings 62 and 63, respectively, by any conventional means, the conductors attached to these brushes then being connected to an external device. A second unidirection motor 75 is provided with an output shaft 76 in axial alignment with output shaft 61. A magnetizable disc, indicated generally at 77, having a structure similar to the disc of FIGS. 1 and 2 but without a central opening, is secured to the end of output shaft 76.

The rotating arm 64 secured to shaft 61 is suitably shaped and dimensioned to hold switch 67 in closely spaced relationship with the base of disc 77 so as to be operated in a manner similar to that described above by any areas magnetized on the surface of disc 77. If the unidirectional motor 60 is arranged to drive output shaft 61 and arm 64 in a clockwise direction, as viewed from above, and if motor 75 is arranged to drive shaft 76 and disc 77 also in a clockwise direction, as viewed from above, motor 60 can be considered as the add motor and motor 75 the subtract motor, application of pulses to these motors having effect similar to that obtained by supplying successive pulses to motors 1 and 4 of the system of FIGS. 1 and 2. It will be evident to one skilled in the art that the arm 64 can advantageously be replaced by a disc of a nonmagnetic material to which a plurality of magnetically operated switches are secured at a variety of radial dis tances. Thus considerable flexibility is also obtained in switch placement. Visual readout is achieved by placing a pointer 78 on shaft 61 and printed numerals on disc 77.

Referring now to FIG. 5, it will be seen that a unidirectional motor 90 is provided with an output shaft 91. One half of a conventional cup-core transformer, indicated generally at 92, is secured to the end of shaft 91 for rotation therewith. An arm 93 is secured to transformer 92 for rotation therewith, the arm being adapted to hold a magnetically sensitive switch 94 in a manner similar to that described with reference to the embodiment of FIG. 4. Suitable apertures are provided in the arm 93 and in the wall of transformer portion 92 to allow the conductors from reed switch 94 to pass therethrough, and to be connected to a winding around a central portion of the core of transformer portion 92, the details of which arrangement will be discussed with reference to FIG. 6. A mounting bracket 95 secured in a fixed location relative to the rotating shaft 91 is provided to hold a second transformer portion, indicated generally at 96, in closely spaced relationship with transformer portion 92, transformer 96 having a central aperture therein to allow shaft 91 to pass through and freely rotate therein. Thus, as output shaft 91 is rotated, carrying transformer portion 92 and arm 93 with its magnetically sensitive switch, transformer section 96 remains fixed. The winding of transformer section 96 is connected to a series circuit including a current. sensitive device 97 and a source of alternating current 98. The output of the current sensitive device 97 is advantageously connected to an amplifier 99 and thence to an external control device. A second unidirectional motor 100 is provided with an output shaft 101, to the free end of which is attached a magnetizable disc 102, similar in structure to disc 77 of the embodiment of FIG. 4.

The embodiment of FIG. 5 eliminates the need for the slip rings of the embodiment of FIG. 4 by using a well known property of transformer devices. As previously described, the terminals of the winding on the transformer section 92, which may be considered as the secondary winding, are connected to the switch 94 which will be actuated by the presence of a magnetized zone on the surface of disc 102. The winding of the other transformer section 96, which may be considered as the primary winding, is connected to external circuitry so that its winding is in series with the current source and a current detector. If switch 94 is open, the winding of primary 96 will draw only magnetizing current and the output of current sensitive device 97 will be at a predetermined level. However, when switch 94 is closed, thereby providing a low impedance path for the secondary winding, the primary 96 will draw significantly greater current. The increased current flow will be detected by device 97 and transmitted through amplifier 99 to the remaining external circuitry as an indication of the closure of switch 94. This arrangement eliminates any mechanical connection between the rotating portions of the embodiment of FIG. 5, using only magnetic phenomena to accomplish the functions desired.

Referring now to FIG. 6, it will be seen in greater detail that the cup-core transformer includes a member 103 which comprises a substantially cylindrical body of ferromagnetic material, having an annular recess 105 extending axially inwardly from one face thereof and having a central opening 107 therethrough. A plurality of windings 106 of a conductor are provided around the central core formed by the annular recess 105. An opening 108 is provided through one wall of the member to allow the ends of the winding to be connected to an external device. The member 92 similarly comprises a substantially cylindrical body 104 with an annular recess inwardly extending from one face thereof, the recess also containing windings 121 about the central core. An opening 122 through an outer wall is provided for wires connected to the ends of the winding. A central hole 125 is provided in the face of the member 104 from which the recess extends, this hole being internally threaded to receive the externally threaded end of the output shaft 91. In use, the members 92 and 96 are mounted with their central axes aligned, both bodies being symmetrical about these axes, so that as the body 92 is caused to rotate about the aligned axes the transformer portions are kept in the same relative relationship, maintaining symmetry in the magnetic lines of flux. The air gap existing between the adjacent faces of the members remain constant throughout rotation, and substantially the same. cross-sectional areas of ferromagnetic material are presented at each position in this rotary movement. Threaded holes 109 and 110 are provided in member 96 to permit bracket 95 to be secured thereto by screws and 132. Similarly, member 92 is provided with an internally threaded hole 123 to allow arm 93 to be secured thereto by machine screw 133.

In the operation of the embodiment of FIG. 5, it will be seen that shaft 91 is driven in one direction by motor 90, which may be, for example, clockwise as viewed from above. The movement of switch 94 relative to the face of disc 102 is then such that the switch moves clockwise relative to the disc in response to each add pulse applied to motor 90. Output shaft 101 is similarly driven by unidirectional motor 100 so as to move disc 102 also in a clockwise direction, as viewed from above, thereby moving the disc 102 in a clockwise direction relative to the switch in response to each subtract pulse supplied to motor 100. Application of a pulse to both motors 90 and 100 simultaneously results in clockwise motion of both the switch and the disc and thus causes zero relative motion.

It will further be seen that, although a magnetizable disc has been shown in each of the embodiments, the invention is not limited thereto, but can be used with a drum or other magnetizable surface which can be attached to the mechanical drive apparatus of the embodiments described.

While certain advantageous embodiments have been chosen to illustrate the invention, it will be understood by those skilled in the art that various changes and modifications can be made therein without departing from the scope of the invention as defined in the appended claims.

What is claimed is:

1. In an electromechanical pulse counting apparatus, the combination of program storage means having selectively magnetized zones on a surface thereof and mounted for rotation about an axis;

sensing means mounted in closely spaced relationship with said surface of said program storage means for sensing the presence of one of said selectively magnetized zones at the portion of said surface of said program storage means nearest said sensing means; first intermittent drive means having an input terminal, to which successive input pulses can be supplied, and an output shaft,

said first intermittent drive means being responsive to each input pulse supplied to said input terminal to rotate said output shaft through an arc of predetermined magnitude in one direction; second intermittent drive means having an input terminal, to which successive input pulses can be supplied, and an output shaft,

said second intermittent drive means being responsive to each input pulse supplied to said input terminal to rotate said output shaft through an arc of predetermined magnitude in one direction; first mechanical coupling means connecting said output shaft of said first intermittent drive means to said program storage means; and

second mechanical coupling means connecting said output shaft of said second intermittent drive means to said sensing means,

said first and second mechanical coupling means being operative to provide relative motion between said program storage means and said sensing means while maintaining said closely spaced relationship.

2. An electromechanical pulse counting apparatus in accordance with claim 1 and wherein said program storage means comprises a flat circular member having at least one surface on which zones can be selectively magnetized.

3. In an electromechanical pulse counting apparatus, the combination of program storage means having a surface magnetized in preselected zones;

sensing means mounted in closely spaced relationship with said surface of said program storage means for scanning said magnetized preselected zones of said program storage means;

means mounting said program storage means and said sensing means for relative motion while maintaining said closely spaced relationship;

first intermittent drive means having an input terminal,

to which successive input pulses can be supplied, and an output shaft,

said first intermittent drive means being responsive to each input pulse supplied to said input terminal to rotate said output shaft through Cir an arc of predetermined magnitude in one direction; second intermittent drive means having an input terminal, to which successive input pulses can be supplied, and an output shaft,

said second intermittent drive means being responsive to each input pulse supplied to said input terminal to rotate said output shaft through an arc of predetermined magnitude in one direction; first mechanical motion transmitting means adapted to transfer said rotational motion of said output shaft of said first intermittent drive means to said program storage means; second mechanical motion transmitting means adapted to transfer said rotational motion of said output shaft of said second intermittent drive means to said sensing means; and circuit means responsive to said sensing means to provide an electrical control signal as a system output in response to said scanning by said sensing means of said magnetized preselected zones of said surface of said program storage means. 4. Apparatus in accordance with claim 3 and in which said sensing means comprises switching means having at least one set of contacts directly operative to function when said relative motion between said program storage means and said switching means causes at least part of said switching means to move into close proximity with at least one of said magnetized preselected zones of said surface of said program storage means. 5. Apparatus in accordance with claim 4 and wherein said circuit means comprises inductive circuit means having a first winding and a second windin g,

said first winding being connected to a series circuit including a source of alternating voltage and a current sensitive device, and said second winding being connected to said at least one set of contacts of said switching means, said first and second windings being inductively coupled, and said current sensitive device being responsive to changes of impedance of said first winding caused by closing and opening of said at least one set of contacts of said switching means. 6. In an electromechanical pulse counting apparatus, the combination of a substantially circular member having at least one selectively matgnetizable surface and having preselected areas of said surface magnetized, and having a centrally located aperture; a mechanical differential having at least a first gear,

a second gear and a third gear,

said first gear of said mechanical differential being secured to an axle rotatably journaled in said centrally located aperture in said substantially circular member, said axle being aligned with a radius of said circular member, and said second gear and said third gear each being in meshing relationship with said first gear; a first unidirectional motor having an input terminal to which successive add input pulses can be supplied, and an output shaft,

said output shaft being secured to said second gear of said mechanical differential, said first unidirectional motor being responsive to each said add input pulse to axially rotate said output shaft through a predetermined angle in a first direction; a second unidirectional motor having an input terminal to which successive subtract input pulses can be supplied, and an output shaft,

10 said output shaft being secured to said third gear at least one sensing device mounted adjacent to said of said mechanical dilferential, at least one selectively magnetizable surface for said first unidirectional motor being responsive to sensing said preselected magnetized area as said each said add input pulse to axially rotate said substantially circular member is rotated. output shaft through a predetermined angle in 5 a direction opposite from said first direction; References Cited said substantially circular member being intermittently UNITED STATES PATENTS rotatable in said first direction by said first gear and 2 546 829 3/1951 Mallina 1 said second gear of sand mechanlcal differential and 3,095,751 7/1963 Enslein 235 92 said output shaft of said first unidirectional motor in 10 response to each add input pulse supplied, and in MAYNARD WILBUR, Primary Emmilwn said opposite direction by said third gear and said second gear of said mechanical differential and said DARYL COOK Exammer' output shaft of said second unidirectional motor in G. J. MAIER, Assistant Examiner.

response to each subtract input pulse supplied; and 15 

